ELASTIC CONSTANTS OF THORIUM SINGLE CRYSTALS

Technical Report · Sat Jun 01 04:00:00 EDT 1957

OSTI ID:4280270

Armstrong, P E; Carlson, O N

Values for the elastic constants c/sub 11/, c/sub 12/, and c/sub 44/ of thorium were determined over the temperature range from 50 to 370 K by ultrasonic measurements on single crystals. Two crystals were prepared by the strain anneal method. Cne crystal was cut in the form of a circular plate about 0.7 inch in diameter and 0.06 inch thick. The STA111! direction of the crystal was perpendicular to the sample face. Measurements on this crystal with a resonance technique produced values for the stiffness coefficient in the STA111! direction. This stiffness coefficient is a function of all three elastic constants: Q STA111! = 1/3(c/sub 11/ + 2c/sub 12/ + 4c/sub 44/). The other crystal was in the form of a plate 0.28 inch thick, 0.5 inch wide, and 1.0 inch long. The direction perpendicular to the 0.6 by 1.0 inch face was found to lie between the STA111! and STA100! directions and close to the (011) plane by the back reflection Laue x-ray method. The cosines of this direction were determined. Measurements of the velocities of the longitudinal mode and the two shear modes that could be propagated in this direction were obtained by the ultrasonic pulse- echo technique. Trial values for the elastic constants were calculated from the direction cosines and the velocity measurements, using a perturbation solution of the equations of motion in a skew direction. These elastic constants were used to calculate values for the stiffness coefficient in the STA111! direction. These values were compared with the results obtained from the resonance method. The differences were assumed to be caused by systematic transit time errors in the pulse-echo method. Allowance for these systematic errors was made by applying small corrections to the measured echo transit times, in proportion to the magnitudes of the times. The corrected transit times were used to calculate velocities from which values were obtained for the elastic constants. At 300 K, c/sub 11/ = 7.53 x 10/sup 11/ dyne-cm/sup -2/, c/sub 12/ = 4.89 x 10/su p 11/ dyne-cm/sup -2/, and c/sub 44/= 4.78 x 10/sup 11/ dyne-cm/sup -2/. The maximum uncertainty in these values is about one per cent. A value of compressibility of 17.3 x 10/sup -13/ cm/sup 2/-dyne/sup -1/ and a value of the anisotropy term, (2c/ sub 44//c/sub 11/-/sup -c12/), of 3.62 were calculated from the elastic constants. (auth)

• Research Organization: Ames Lab., Ames, Iowa
• DOE Contract Number: W-7405-ENG-82
• NSA Number: NSA-13-010854
• OSTI ID: 4280270
• Report Number(s): ISC-993
• Country of Publication: United States
• Language: English

Related Subjects

ANISOTROPY
ANNEALING
CHEMISTRY
COMPRESSIBILITY
CONFIGURATION
DEFORMATION
ELASTICITY
EQUATIONS
ERRORS
MACHINING
MEASURED VALUES
MONOCRYSTALS
MOTION
NUMERICALS
PERTURBATION THEORY
PLATES
PREPARATION
PULSES
QUANTITATIVE ANALYSIS
REFLECTION
RESONANCE
TEMPERATURE
THORIUM
ULTRASONICS
VELOCITY
X RADIATION